Press apparatuses for assembling building trusses from arranged components have generally included a layout or work table upon which the components are assembled and held in place by jig fixtures and a press mechanism which has involved the use of one or more hammers or pressure plates which drive the nail plates in to the truss components. When the nail plates have been driven into the assembled components a truss joint is formed. When all of the required truss joints have been secured by nail plates or connector plates the completed building truss is removed from the work table.
U.S. Pat. No. 3,172,125 to Sanford shows a truss fabricating apparatus with five stamping stations which are separated to provide work bays. The stamping stations contain hydraulic cylinders and hammers which can be positioned over individual truss joints for pressing in a connector plate. The truss components are arranged by a hand layout operation within the stamping stations and after fabrication the truss is removed by a roller conveyor which forms part of the stamping stations. Personnel working on such a truss fabricating apparatus must work between, under and around the press stations during fabrication.
U.S. Pat. No. 3,379,354 to Moehlenpah et al shows an assembly work station with a single C-shaped hydraulic press which is movable to various individual component joints in order to drive in the connector plates.
U.S. Pat. Re. No. 27,692 to Post shows an assembly apparatus in which a series of base supports are used to mount upstanding C-clamp stands. In use, the operating personnel must adjust the clamp stands on the supporting base supports and then place the truss components into the stands under the C-clamp presses one component at a time prior to securing the joints with connector plates. U.S. Pat. Nos. 3,771,439 to Mort and 3,388.65 to Jureit show truss assembly apparatus similar to that shown in Post.
U.S. Pat. No. 3,826,188 to Eberle, shows a truss fabricating machine which has a frame on which hydraulic cylinders and platens are mounted. This type of press machine requires movement of the frame along the work table and adjustment of the hammers at each station in order to drive in the individual connector plates. U.S. Pat. No. 4,441,643 shows a similar apparatus for the fabrication of loading pallets.
U.S. Pat. No. 3,329,328 to Jureit et al shows a truss fabricating apparatus in which a series of fixed C-frame clamps are employed for manufacturing a bow string truss. This apparatus does not have variability sufficient to produce other trusses such as monopitch trusses.
U.S. Pat. No. 3,334,580 to Smith, shows an early form of a truss fabricating apparatus in which a carriage operated a single drop hammer to drive connector plates into truss joints.
U.S. Pat. No. 3,443,513 to Jureit et al, shows an elongated conveyor work table which is outfitted with a single press 12 under which the truss to be formed is moved for a series of connector plate assembly steps. U.S. Pat. Nos. 3,602,237, 3,603,244 both to Jureit et al and 4,104,962 to Castillo are similar in regard to the use of a single press station.
Other patents dealing with truss fabrication apparatus are: U.S. Pat. Nos. 4,241,651; 4,081,120; and 4,184,621.
The prior art as represented by the above mentioned patents required operators to assemble the truss components in and around and under various press heads and hammers. Such a manufacturing process is characterized by a high labor cost component since individual placement of the components must be made in and around a number of pressing heads which have to be accessed by the operator who must then move between various work stations and pressing stations. The alternative is to employ multiple personnel which also raises the labor costs.
The prior art presses are also characterized by requiring the operators to move the hammers or press plates to multiple locations on each truss during the fabrication process. This results in high unit production costs due to operator time expenditure.
The fabrication of building trusses is becoming a highly cost competitive manufacturing business. Lower unit production costs are required which then forces higher productivity and low labor costs for the truss fabrication process.
Another cost element in the truss fabrication business is that operator safety is of particular concern with respect to plant operating insurance policies and OSHA (Occupational Health and Safety Adminstration) regulations.
The evolving requirements for truss fabrication apparatus and the manufacturing process carried out thereby require improvements for higher productivity and hence lower unit production costs.
The present invention solves the above problems in the prior truss fabrication apparatus by providing a jig table upon which the truss components can be assembled in a secured truss formation together with connector plates without the necessity for the operator to work in and around the press platens which drive the connector plates into the components. The jig table is then power driven to a position under a gantry press system which is easily adjustable to accomodate different pressing positions for the fabrication of a wide range of building truss. After fabrication the building truss is quickly and conveniently removed from the truss press.
By use of the truss press of the present invention higher productivity and lower unit production costs for building truss is possible. Safety of operation is also assured.